The specific goals for Core C are: 1) establishment of lymphoblastoid cell lines and fibroblast cultures on LFS and WT patients. 2) isolation of DNA, RNA, and plasma from peripheral blood; and DNA and RNA from tumor and normal tissue samples from study individuals. This includes those with Wilms tumors, those who are potential p53 mutation carriers, and family members of these individuals. 3) mutation detection by direct sequencing of PCR products for p53, WT1, and/or some WT "pathway" genes for childhood sarcoma kindreds, Wilms tumor kindreds, and sporadic Wilms tumors 4) Southern analysis of WT patients to identify WT1 deletions undetectable by PCR-based sequencing. 5) functional characterization of odd p53 missense mutations and identification of potentially truncated proteins in cells from individuals carrying nonsense and splicing mutants 6) mutation screening by WAVE analysis for selected WT pathway genes identified in Project 4 7) storage and distribution, as needed, of DNA, RNA, and plasma samples 8) maintenance of a database detailing sample handling, nucleic acids isolations, and mutational analysis. This database will be used to update the Program's database managed by Core C. 9) archiving of sequence and mutation screening output. These functions are critical to the success of all projects within the P01. Project 1 uses p53 and WT1 data to characterize better cancer risk and also to develop better genetic models for cancer predisposition. The information regarding p53 mutational status will also identify non-p53 families that will aid the identification (Proj. 2) of other genes responsible for predisposition and guide the interpretation of the tumor data generated from mutant mice (Projects 3 & 5). WT1 mutational status is critical for the delineation of the molecular subsets of Wilms tumors and WT patients and elucidating the biologic effect of the pattern of mutations, alterations, and expression changes we have previously identified in Wilms tumors (Project 4). This core provides sample processing, mutation screening and analyses, functional analyses, sample storage, and data storage critical for all projects of the P01.